Traditionally, when grapes intended for raisins were ready to be harvested, they were picked by hand and placed on trays or paper placed adjacent to the rows of grapevines. The grapes were then dried by the sun for 17-21 days to produce raisins.
Raisin grapes can also be harvested mechanically. In one approach, the grape-laden canes of the grapevine are cut by hand, and later, a machine moves down the grapevine rows collecting the plant matter (e.g., canes, leaves, etc.) and grapes. The harvester transfers the grapes, via a conveyor belt, to another machine towed by a tractor in the adjacent row. The harvester may remove some of the plant matter. The second machine lays down a continuous layer of paper along the row and spreads the grapes thereon. After the grapes have suitably dried to become raisins, a third machine collects the raisins from the paper and transfers the raisins to a fourth machine in an adjacent row that deposits the raisins into bins for transportation and/or further processing. While mechanical harvesting offers many advantages over manual harvesting such as lower labor costs, it still involves the use of multiple machines and multiple passes through the vineyard which increases the chance of damage to the vines and also increases operating costs.
Grapevines are commonly grown along a trellis system. Typical trellis options for grapevines include conventional trellises, open gable trellises and overhead trellises. In an overhead trellis system, the grapevines are planted in a row, and their canes are trained to grow across a grid of intersecting wires running across the gaps between the rows of grapevines.
The type of trellis system influences the harvesting method of the grapes. For instance, the mechanical harvesting system described above is typically used to harvest grapes grown on a conventional or open gable trellis. Such harvesting methods, however, are not suitable for grapes grown on overhead trellis because the machinery cannot drive down the rows.
An overhead trellis system is advantageous for dried-on-the-vine harvesting. When the grapes are ready to be harvested, the canes are cut and the grapes are left to dry on the vine, about 6-8 weeks. After the grapes are suitably dried, a mechanized harvester travels down the rows, underneath the overhanging trellis wires, and collects the hanging raisins. Mechanical harvesters for dried-on-the-vine harvesting are typically low-profile, self-propelled vehicles and use a series of tubes or teeth, usually made of plastic, to vibrate the plant matter and grapes for collection into bins.
While self-propelled mechanical harvesters are commonly used for dried-on-the-vine harvesting, they can be expensive. The weight and height (e.g., clearance from the ground) of self-propelled mechanical harvesters may cause them to become stuck in mud or uneven ground. Therefore, it is desirable to provide a mechanical harvester that is more cost-effective, versatile (e.g., capable of adjustment in the field), forgiving, and that will not cause undue damage to the harvester, the trellis and/or grapevines.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.